The long-term goal of the proposed research is to develop and commercialize a cost-effective product for the treatment of chronic low back pain of muscular origin by using intramuscular electrical stimulation (IMES). In IMES, wire electrodes are temporarily implanted into muscles through the skin and connected to a portable stimulator for several weeks of stimulation treatment. The IMES product and treatment are expected to be: (1) more effective than transcutaneous electrical nerve stimulation (TENS) and conventional neuromuscular electrical stimulation (NMES) as the IMES uses intramuscular instead of skin-surface stimulation, permitting more intense and specific stimulation; (2) more effective than percutaneous electrical nerve stimulation (PENS) as the IMES uses indwelling wire electrodes instead of acupuncture needles, permitting more frequent and longer-lasting treatment sessions on a daily basis for many weeks; and (3) more convenient to use than the PENS as patients only need to visit the clinic once for electrode insertion and once for electrode pull-out instead of many treatment visits, saving time and money. A case-series clinical study will be conducted to assess the feasibility of the proposed IMES product and treatment. Specifically, (1) a total of 10 subjects with chronic low back pain will be enrolled in the study according to the proposed subject eligibility criteria; (2) a set of 8 intramuscular electrodes will be implanted into the low back muscles of each subject according to the proposed protocol; (3) a 6-week stimulation treatment will be completed in at least 8 subjects according to the proposed paradigm; (4) a complete set of data will be collected and analyzed on the results of the IMES treatment according to the proposed outcome measures and data collection schedule. The proposed Phase I feasibility study is critical to the ultimate market success of the IMES product. Specifically, (1) the clinical experience gained and experimental data collected during the Phase I study will provide a firm basis for the design of a pivotal randomized controlled trial to demonstrate the safety and effectiveness of the device and treatment in a Phase II study; and (2) the design and test results of the prototype device used in the Phase I study will provide a firm basis for the refinement of the product design during the Phase II study.